Wastewater and Bioventing Treatment Systems for Acid Mine Drainage–Contaminated Soil

ABSTRACT

Acid mine drainage (AMD) has continued to be a major threat leading to the destruction of the ecosystem and contamination of soil and waterbodies. The high sulfate concentration of AMD lowers the soil pH, making the soil more acidic and less productive which contributes to a reduction in the availability of arable land for agricultural purposes. Biological treatment has offered a cost-effective and eco-friendly approach through the introduction of organic substrates, aeration, or genetically modified microorganism to stimulate the contaminated environment and enhance sulfate reduction as opposed to previously used physicochemical methods which were criticized due to their inefficient and non-ecofriendly nature. This study focused on the evaluation of biological treatment through the application of wastewater (biostimulation) and air-injection (bioventing) for sulfate removal from AMD-contaminated soils. AMD-contaminated soil was amended with brewery (BWW) and municipal wastewater (MWW) at varying loading ratios to investigate the possible synergy while atmospheric air was supplied to bioventing treatments only. All treatments were conducted at mesophilic conditions for 28 days. The inability to improve sulfate removal rate through air-injection can be attributed to biosulfidogenesis preference for anoxic as against (high) oxic conditions for optimum performance. The BST and BVT treatment resulted in 34–53% and 27–42% sulfate removal efficiency, respectively. This study showed the efficacy of wastewater biostimulations and bioventing as a promising approach for sulfate and heavy metal removal from AMD-contaminated soils. The techniques have the potentials as vital tools for the mitigation of pollution aftermath in affected communities.

KEYWORDS:

• Acid mine drainage
• bioventing
• municipal wastewater
• biostimulation
• sulfate-reducing bacteria